Methods have been developed for preparing L-canavanine, L-canaline, O-ureidohomoserine, and L-canavaninosuccinic acid. These compounds, collectively designated the canalineurea cycle amino acids, are naturally-occurring structural analogues of the ornithineurea cycle intermediates and possess potent antimetabolic properties. Fundamental studies of the biological effects and mode of action of these amino acid analogues are being conducted with the aquatic plant, Lemna minor, and the tobacco hornworm, Manduca sexta. These studies are designed to provide fundamental information on the antimetabolic properties of amino acid analogues and to encourage their employment as a research tool.